从Python中的构造函数__init__内省参数 [英] Introspecting arguments from the constructor function __init__ in Python

问题描述

从__init__中提取参数而不创建新实例的方法是什么. 代码示例:

What is a way to extract arguments from __init__ without creating new instance. The code example:

class Super:
    def __init__(self, name):
        self.name = name

我正在寻找类似Super.__dict__.keys() type的解决方案.只是检索名称参数信息而无需添加任何值.有这样的选择吗?

I am looking something like Super.__dict__.keys()type solution. Just to retrieve name argument information without adding any values. Is there such an option to do that?

推荐答案

针对Python 3.3+的更新(如指出的那样beeb 在评论中)

Update for Python 3.3+ (as pointed out by beeb in the comments)

您可以使用 inspect.signature 在Python 3.3中引入:

You can use inspect.signature introduced in Python 3.3:

class Super:
    def __init__(self, name, kwarg='default'):
        print('instantiated')
        self.name = name

>>> import inspect
>>> inspect.signature(Super.__init__)
<Signature (self, name, kwarg='default')>

下面的原始答案

您可以使用 inspect

You can use inspect

>>> import inspect
>>> inspect.getargspec(Super.__init__)
ArgSpec(args=['self', 'name'], varargs=None, keywords=None, defaults=None)
>>> 

inspect.getargspec实际上并没有创建Super的实例，请参见下文:

inspect.getargspec doesn't actually create an instance of Super, see below:

import inspect

class Super:
    def __init__(self, name):
        print 'instantiated'
        self.name = name

print inspect.getargspec(Super.__init__)

这将输出:

### Run test.a ###
ArgSpec(args=['self', 'name'], varargs=None, keywords=None, defaults=None)
>>> 

请注意，instantiated从未打印过.

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